The present invention relates to a state monitoring method and apparatus in a subscriber line test between a telephone exchange and an ADSL (Asymmetric Digital Subscriber Line) apparatus.
Two kinds of control on the POTS (Plain Ordinary Telephone Service) subscriber line and ADSL subscriber line are required for a subscriber who is receiving a POTS, which is an existing telephone service through a telephone exchange, and an ADSL service, which is asymmetric digital subscriber line communication. Since POTS control in a telephone exchange and ADSL control in an ADSL apparatus are mutually independent, it is impossible for the telephone exchange to know the state of the ADSL apparatus, and vice versa. For this reason, a line blocked state due to a line test instruction from one control terminal looks like a fault to the other control terminal.
FIG. 4 shows a conventional communication system. The conventional communication system shown in FIG. 4 is comprised of a subscriber 3 constituted by a telephone 31 and terminal 32, a multiplexing/matching circuit 8 to which the telephone 31 and terminal 32 are connected and which executes line matching and modulates/multiplexes a voice signal from the telephone 31 and a data signal from the terminal 32 in different frequency bands, a demultiplexing circuit 9 for demultiplexing the multiplexed voice signal and data signal, a telephone exchange 1 for receiving the voice signal from the demultiplexing circuit 9, an ADSL control section 21 for receiving the data signal from the demultiplexing circuit 9, a control terminal 4 which is connected to the telephone exchange 1 to maintain and manage the telephone exchange 1, a data network 7 to which an ADSL apparatus 2 is connected, a control terminal 5 which is connected to the data network 7 to maintain and manage various units subordinate to the data network 7, and a PSTN 6 to which the telephone exchange 1 is connected.
The telephone exchange 1 includes a POTS control section 11 which is a subscriber circuit of the telephone exchange 1 and sends a telephone voice signal to a PSTN (Public Switched Telephone Network) upon converting it into a digital signal, and a host apparatus 12 for controlling transmission/reception of the voice data as the digital signal. The ADSL apparatus 2 includes the ADSL control section 21, which is a subscriber circuit of the ADSL apparatus 2, and a host apparatus 22 for controlling transmission/reception of data signals to/from the terminal 32.
In the conventional communication system having the above arrangement, the control terminal 5 on the ADSL apparatus 2 side knows nothing about a line test instruction from the control terminal 4 on the telephone exchange 1 side. For this reason, the control terminal 5 determines even a line blocked state for a line test as a line blocked state of the subscriber 3, i.e., a fault.
It is an object of the present invention to provide a state monitoring method and apparatus in a subscriber line test, which can notify one control terminal of a line blocked state due to a line test instruction from the other control terminal when a control terminal on the POTS side in a telephone exchange and a control terminal on the ADSL side in an ADSL apparatus exist independently of each other.
In order to achieve the above object, according to the present invention, there is provided a state monitoring method in a subscriber line test in a communication system in which a subscriber telephone and a subscriber terminal are independently connected to a telephone exchange and an ADSL (Asymmetric Digital Subscriber Line) apparatus through a subscriber line, comprising the steps of connecting, through an interface, the telephone exchange to which a first control terminal is connected to the ADSL apparatus to which a second control terminal is connected, notifying a line blocked state due to a line test instruction from one of the first and second control terminals to the other of the first and second control terminals through the interface, and causing the other of the first and second control terminals to determine, when receiving a notification of the line block state due to the line test instruction, that the line blocked state is not caused by a fault.